It is known in the art of designing drive trains for motor vehicles, such as automobiles and trucks, to provide for differential action between driving wheels carried at opposite ends of an axle assembly of the vehicle. Typically, the axle is divided into two parts with inner ends of the separate axle parts splined to drive gears contained within a differential assembly. The differential assembly, in turn, contains an arrangement of gearing which permits driving action to be delivered through the assembly and to the separate drive gears in accordance with preferred modes of operation for various driving conditions. It is also known to provide for a locking of the ends of the separate axle parts within the differential assembly itself through the use of locking rings (or C-shaped fasteners) which are fitted within annular grooves formed near the ends of the axles. In order to assemble separate axle ends into a standard differential assembly, it is necessary to provide for some relative motion between the axle and the differential case so that each axle end can be inserted within the differential case for a sufficient distance to expose the locking ring groove associated with the axle end. Once the locking ring is installed in place, the axle part is then pulled outwardly from the differential case to a position where it is maintained for normal driving operation. When this is done for both axle parts of the drive assembly, it is necessary to insert some means for maintaining the two axle ends in their outwardly disposed positions so as to prevent axial movement of the axles and to maintain the locking rings within a captured position. Standard differential assemblies which use bevel gears as the drive gears for the axle sections can use a large pin or shaft for maintaining the two axle ends in a spaced apart condition once the locking rings have been installed and the axle parts have been moved to their operating positions. Prior patents showing such arrangements include U.S. Pat. Nos. 3,400,611; 3,527,120; and 3,874,250.
The installation of a differential mechanism, other than a bevel gear type of mechanism, in an axle housing presents a different problem for maintaining correct spacing between the axle ends if the differential is of a type that does not include a shaft or a pin disposed along an axis that intersects the common axis of the axles. An example of such a differential assembly is disclosed in U.S. Pat. No. 2,859,641 of Nov. 11, 1958 in the name of Gleasman, which patent is hereby incorporated by reference for purposes of describing specific details of a type of differential assembly which does not utilize bevel gears for obtaining differential action in a drive train. The patent discloses a mechanism termed a "cross axis compound planetary gear complex". This type of differential includes worm gears coupled to each axle end as drive gears together with so called "balancing" gears or transfer gears associated with each of the worm drive gears and in mesh with each other for transferring and dividing torque between the axle ends. The transfer gears are mounted in pairs, and each transfer gear of a pair rotates on an axis of rotation that is substantially tangental to the pitch of an associated axle drive gear. With the specific type of arrangement disclosed in the aforesaid Gleasman patent, it is not feasible to provide a shaft between the axle drive gears to maintain the ends of the axles in spaced apart positions because such a shaft would interfere with the positions of the transfer gears carried by the assembly. In order to provide for correct spacing of the axle ends within the Gleasman type of differential assembly, spacing blocks have been designed for insertion between the axle ends when a bifurcated thrust member is removed from one end of the assembly (as disclosed in co-pending applicaton Ser. No. 475526 entitled "Differential Gearing Assembly" and filed even date herewith in the name of Vernon E. Gleasman) or when an idler gear means, positioned between a pair of transfer gears, is removed for providing access to the central part of the differential assembly for insertion of a bifurcated spacing block (as disclosed in co-pending application Ser. No. 475528 entitled "Differential Gearing Assembly", filed even date herewith, in the name of Vernon E. Gleasman).
In the latter arrangement, an intermediate idler gear is arranged to not only drivingly connect a pair of transfer gears but also to span an access opening formed in the differential case so that removal of the intermediate gear opens a clearance space between all gear components which is sufficient for a spacing block to be installed and removed from the differential case. In this arrangement the intermediate gearing comprises spur gear elements mounted on a journal pin for meshing engagement with spur gear portions of each of the pair of transfer gears associated therewith. The journal pin is arranged for easy removal and installation relative to the differential case and serves to fix the position of the intermediate idler gear relative to the differential case.